Friday, August 31, 2007

Meat is the leading cause of global warming

That is the slogan-ized version of the conclusion of two recent studies on the affect of animal agriculture on global climate. This report from the UN Food and Agriculture Organization shows that "The livestock sector [is] responsible for 18 percent of all greenhouse gas emissions, measured in CO2 equivalent," which is more than all forms of transportation combined. And this conclusion is only one of several the UNFAO group draws showing the environmental damage of livestock. This study from geophysicists at the University of Chicago, and published in a journal called Earth Interactions, shows that "the greenhouse gas emissions of various diets vary by as much as the difference between owning an average sedan versus a sport-utility vehicle under typical driving conditions." That is, you could trade your Hummer for a Toyota, but it wouldn't do as much good as going vegetarian.

These studies are driving a campaign by major animal rights groups to link meat eating with global warming, highlighted in this NYT article (from Molly, via email.) I hope the campaign takes off. Past efforts to highlight this link generally get bogged down in jokes about cow farts. People have this immediate sense that if you are worried about cow farts, you must be some sort of moral busybody who wants to regulate everything. Cows are going to fart, how can you stop that? It helps to remember that the number of cows on the planet is not some pre-ordained fact. It is something we are responsible for. And hence, we are responsible for their mess.

8 comments:

I think it's a mistake to focus too much on diet. Methane emissions and global population have always tracked very closely. While they could probably be modified mildly by encouraging people to change their diet, I think there are very good reasons to be skeptical about this have more than a minimal impact. CO2 emission, on the other hand, can be reduced through public policy in a way that Methane can't. And in the end, it's public policy and not individual initiative that has any chance of seriously curbing greenhouse gas emissions.

Furthermore, I think it's a mistake to look too hard to synergy amongst different causes. By the same logic, shouldn't we be encouraging people to give up rice? It makes up a great deal of anthropogenic methane emissions. If you focus on beef and not rice, it may lead people to conclude that concern about global warming is a handy stick to use to whack an already existing hobby horse.

I don't understand why methane emissions are less amenable to public policy solutions than CO2. In each case there is an industry which can be reformed and consumption which can be reduced. Simply pointing out the correlation between population levels and methane emissions doesn't get at the causes we can actually manipulate to reduce greenhouse gases.

Also, people underestimate the degree to which individual initiative can affect public policy. You may not accomplish much by buying a hybrid. (You might accomplish nothing, in fact, if you take into account that you free up the manufacturer to legally make another car that gets worse millage) But the popularity of hybrid vehicles demonstrates to the government that there is a push for conservation and it demonstrates to manufacturers that there is a market for green cars.

I know rice is a methane source, but can you document that it is as big a factor in climate change as animal agriculture and transportation?

People need energy, as long as it does what it wants they don't necessarily care what source it's from. There seems to be a lot more plausible elasticity here than with methane, which can largely be changed through, as you say, diet. The Burkean in me sees in the methane emmission/human population tracking a strong tendency about human behavior regarding diet. People don't much care, I think, whether their power comes from clean sources or coal, as long as the lights are on. Diet, I think is far more embedded in deep cultural patterns (not to mention survival strategies, esp. regarding rice), and the small-c conservative in me sees far less room for change amongst the vast majority of the world's populations.

(Please don't think I'm taking issue with the claim that as a normative matter, those who can *should* restrict beef intake for a variety of reasons, one of the biggest ones being global climate change.)

I was digging around on this when I first read your post, and someone I found said rice cultivation is generally assumed to be responsible for 10-30% of anthropogenic methane emissions, which is admittedly a large range, but there are some uncertainties. I found that stuff on a computer half a world away, and I'm about to crash with jetlag so I can't track down a link for you at the moment, but this fits with what I seem to recall back when I was teaching this stuff and staying on top of it better a few years ago.

Agreed, certainly. There's also dry-cultivation methods for rice that virtually eliminate methane emissions for rice, although for those who grow rice for survival in tropical climates, I'm not sure how realistic it is. And leftover rice husks can be burned for power, which makes the emissions from rice production far more efficient--Thailand is a leader on this front, IIRC. And, of course, an added wrinkle is that GW may reduce rice yields. In the next few days I'll pull together a post on this, hopefully.

Population size is another of those hard-to-adjust multipliers in global warming. But it's a multiplier in all our other environmental problems too, which leads me to believe that, really, it's the root of the problem. There's too damn many people on the planet.Just and humane ways of changing that in the short term are of course problematic. In the longer term, it looks like educating women and providing access to reliable contraception does the trick without coercive policies.

I think rice feeds many more people than beef, and does it in a more cost-effective manner, and (assuming this is true) it is thus much more costly to obtain the same greenhouse gas reduction.

I have read that beef is an enormously inefficient way of turning corn into calories, so much so that a bicyclist fueled by beef (not the usual case; pasta is the traditional source of the extra calories) is less fuel-efficient than an automobile.